With respect to TCRs, mention is made of international patent application Serial No. PCT/GB2005/001924 filed on May 18, 2005 which published as WO/2005/113595 on Dec. 1, 2005 and U.S. application Ser. No. 11/596,458 filed on Nov. 13, 2006, both incorporated herein by reference.
The YLEPGPVTA (SEQ ID NO: 1) peptide corresponds to amino acid residue numbers 280-288 of human glycoprotein 100 (gp100) protein. Gp100 is widely, and significantly overexpressed on melanoma cancer cells. For example, one study (Trefzer et al., (2006) Melanoma Res. 16(2): 137-45) found that 82% of 192 melanoma metastases from 28 melanoma patients expressed gp100. Several studies reported higher expression levels of gp100 in melanoma tissues (Hofbauer et al., (2004) J Immunother. 27(1): 73-8, Barrow et al., (2006) Clin Cancer Res. 12:764-71). The YLEPGPVTA (SEQ ID NO: 1) peptide is presented by Class I HLA molecules on gp100+/HLA-A2 cancer cells. (Salgaller et al., (1996) Cancer Res 56: 4749-4757)
Therefore, the YLEPGPVTA (SEQ ID NO: 1) HLA-A2 complex provides a cancer marker that the TCRs of the invention can target. For example, TCRs of the invention may be used for the purpose of delivering cytotoxic agents to the cancer cells, or may be transformed into T-cells, rendering them capable of destroying tumour cells presenting that HLA complex, for administration to a patient in the treatment process known as adoptive therapy. However, for the former purpose it would be desirable if the TCRs had a considerably higher affinity and/or considerably slower off-rate, so that the TCRs reside on the targeted tumour cells for an extended period of time. For the latter purpose, it would be desirable if the TCRs had somewhat a higher affinity and/or a slower off-rate for the peptide-HLA complex than native TCRs specific for that complex, but not as high affinity as for the former purpose. Dramatic increases in affinity have been associated with a loss of antigen specificity in TCR gene-modified CDS T cells, which could result in the nonspecific activation of these TCR-transfected CDS T cells, so intermediate affinity TCRs would be preferred for adoptive therapy (see Zhao et al., (2007) J Immunol. 179: 5S45-54; Robbins et al., (200S) J Immunol. 180: 6116-31; and see also published WO 200S/03S002). The present invention provides such TCRs.
TCRs are described using the International Immunogenetics (IMGT) TCR nomenclature, and links to the IMGT public database of TCR sequences. Native alpha-beta heterodimeric TCRs have an alpha chain and a beta chain. Broadly, each chain comprises variable, joining and constant regions, and the beta chain also usually contains a short diversity region between the variable and joining regions, but this diversity region is often considered as part of the joining region. Each variable region comprises three CDRs (Complementarity Determining Regions) embedded in a framework sequence, one being the hypervariable region named CDR3. There are several types of alpha chain variable (Vα) regions and several types of beta chain variable (Vβ) regions distinguished by their framework, CDR1 and CDR2 sequences, and by a partly defined CDR3 sequence. The Vα types are referred to in IMGT nomenclature by a unique TRAV number. Thus “TRAV17” defines a TCR Vα region having unique framework and CDR1 and CDR2 sequences, and a CDR3 sequence which is partly defined by an amino acid sequence which is preserved from TCR to TCR but which also includes an amino acid sequence which varies from TCR to TCR. In the same way, “TRBV19” defines a TCR Vβ region having unique framework and CDR1 and CDR2 sequences, but with only a partly defined CDR3 sequence.
The joining regions of the TCR are similarly defined by the unique IMGT TRAJ and TRBJ nomenclature, and the constant regions by the IMGT TRAC and TRBC nomenclature.
The beta chain diversity region is referred to in IMGT nomenclature by the abbreviation TRBD, and, as mentioned, the concatenated TRBD/TRBJ regions are often considered together as the joining region.
The α and β chains of αβ TCR's are generally regarded as each having two “domains”, namely variable and constant domains. The variable domain consists of a concatenation of variable region, and joining region. In the present specification and claims, the term “TCR alpha variable domain” therefore refers to the concatenation of TRAV, and TRAJ regions, and the term TCR alpha constant domain refers to the extracellular TRAC region, or to a C-terminal truncated TRAC sequence. Likewise the term “TCR beta variable domain” refers to the concatenation of TRBV and TRBD/TRBJ regions, and the term TCR beta constant domain refers to the extracellular TRBC region, or to a C-terminal truncated TRBC sequence.
The unique sequences defined by the IMGT nomenclature are widely known and accessible to those working in the TCR field. For example, they can be found in the IMGT public database. The “T cell Receptor Factsbook”, (2001) LeFranc and LeFranc, Academic Press, ISBN 0-12-441352-8 also discloses sequences defined by the IMGT nomenclature, but because of its publication date and consequent time-lag, the information therein sometimes needs to be confirmed by reference to the IMGT database.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.